package com.test.mess;

import java.math.BigInteger;
import java.util.Date;
import java.util.Random;
import java.util.zip.CRC32;


public class KeyGen {

    /**
     * @param s
     * @param i
     * @param bytes
     * @return
     */

    public static short getCRC(String s, int i, byte bytes[]) {

        CRC32 crc32 = new CRC32();

        if (s != null) {

            for (int j = 0; j < s.length(); j++) {

                char c = s.charAt(j);

                crc32.update(c);

            }

        }

        crc32.update(i);

        crc32.update(i >> 8);

        crc32.update(i >> 16);

        crc32.update(i >> 24);

        for (int k = 0; k < bytes.length - 2; k++) {

            byte byte0 = bytes[k];

            crc32.update(byte0);

        }

        return (short) (int) crc32.getValue();

    }


    /**
     * @param biginteger
     * @return String
     */

    public static String encodeGroups(BigInteger biginteger) {

        BigInteger beginner1 = BigInteger.valueOf(0x39aa400L);

        StringBuilder sb = new StringBuilder();

        for (int i = 0; biginteger.compareTo(BigInteger.ZERO) != 0; i++) {

            int j = biginteger.mod(beginner1).intValue();

            String s1 = encodeGroup(j);

            if (i > 0) {

                sb.append("-");

            }

            sb.append(s1);

            biginteger = biginteger.divide(beginner1);

        }

        return sb.toString();

    }


    /**
     * @param i
     * @return
     */

    public static String encodeGroup(int i) {

        StringBuilder sb = new StringBuilder();

        for (int j = 0; j < 5; j++) {

            int k = i % 36;

            char c;

            if (k < 10) {

                c = (char) (48 + k);

            } else {

                c = (char) ((65 + k) - 10);

            }

            sb.append(c);

            i /= 36;

        }

        return sb.toString();

    }


    /**
     * @param name
     * @param days
     * @param id
     * @return
     */

    public static String MakeKey(String name, int days, int id) {

        id %= 100000;

        byte bkey[] = new byte[12];

        bkey[0] = (byte) 1; // Product type: IntelliJ IDEA is 1

        bkey[1] = 14; // version

        Date d = new Date();

        long ld = (d.getTime() >> 16);

        bkey[2] = (byte) (ld & 255);

        bkey[3] = (byte) ((ld >> 8) & 255);

        bkey[4] = (byte) ((ld >> 16) & 255);

        bkey[5] = (byte) ((ld >> 24) & 255);

        days &= 0xffff;

        bkey[6] = (byte) (days & 255);

        bkey[7] = (byte) ((days >> 8) & 255);

        bkey[8] = 105;

        bkey[9] = -59;

        bkey[10] = 0;

        bkey[11] = 0;

        int w = getCRC(name, id % 100000, bkey);

        bkey[10] = (byte) (w & 255);

        bkey[11] = (byte) ((w >> 8) & 255);

        BigInteger pow = new BigInteger("89126272330128007543578052027888001981", 10);

        BigInteger mod = new BigInteger("86f71688cdd2612ca117d1f54bdae029", 16);

        BigInteger k0 = new BigInteger(bkey);

        BigInteger k1 = k0.modPow(pow, mod);

        String s0 = Integer.toString(id);

        String sz = "0";

        while (s0.length() != 5) {

            s0 = sz.concat(s0);

        }

        s0 = s0.concat("-");

        String s1 = encodeGroups(k1);

        s0 = s0.concat(s1);

        return s0;

    }


    public static void main(String[] args) {

//        if (args.length == 0) {
//
//            System.err.printf("*** Usage: %s name%n", KeyGen.class.getCanonicalName());
//
//            System.exit(1);
//
//        }

        Random r = new Random();

        System.out.println(MakeKey("hengter", 0, r.nextInt(100000)));

    }

}